Certain food or beverage-containing packages include products that are either hot filled, thermally pasteurized or sterilized after filling, and/or products where the entire package (filled container sealed with a closure applied thereon) is subjected to “retorting” (i.e., heating the package to a temperature greater than 220° F.). Plastic containers and, more particularly, the plastic container finishes that are subjected to retort or other high temperature processes often undergo expansion and subsequent contraction. The expansion and contraction of the container finish can often affect the integrity of the seal between the container and the closure, thus making it possible for the product to become contaminated or otherwise negatively affected.
Composite closures have commonly been used with packages that are subjected to retort or other high temperature applications. Composite closures typically include, an annular shell or ring with a central opening and a separate end panel occupying the central opening. Many of the currently available composite closures include a metal end panel and an annular gasket or liner of sealant that provides a hermetic seal between the closure and the container finish. In addition to being effective in maintaining seal integrity during retort, the metal end panel of the metal/plastic composite closure provides a good barrier to oxygen which, if allowed to freely permeate the package, can result in spoilage of the food product.
Recently, composite closures where the end panel is made substantially of a non-metal material, such as plastic, have been disclosed. Such “all-plastic” composite closures have the advantage of the end panel being less susceptible to corrosion and are more economical to manufacture. Even more recently, “one-piece” closures (i.e., non-composite closures) in retort or other high temperature applications have also been disclosed. One example of such a closure is provided in U.S. Pat. No. 6,702,133.
Maintaining the integrity of the seal can be particularly problematic in food products packaged in plastic containers that are subjected to retorting. Thus, there is a continuing need for a closure and package with a closure that can be subjected to retort while maintaining the integrity of the seal. In addition, there exists a continuing need to provide a retortable package that (1) seals the package to further limit oxygen ingress at the interface of the container finish and closure cap, (2) effectively limits the ingress of oxygen through the closure, (3) provides evidence of tampering and reduces the risk of tampering, and (4) reduces the cost of manufacture. The packages and closures of the present invention address the above-stated needs.